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Effect of crystallization on optical properties of sol-gel processed nano-sized strontium titanate (SrTiO3) thin films
Published online by Cambridge University Press: 17 February 2009
Abstract
Strontium titanate (SrTiO3) or ST thin films have been prepared using
strontium 2-ethylhexanoate
[ Sr[ CH3(CH$_{2})_{3}$CH(C2H5)CO2] 2] and
titanium(IV) isopropoxide Ti[ OCH(CH$_{3})_{2}$
] 4 as precursors using
a modified sol-gel processing technique. The precursor
[ Sr[ CH3(CH$_{2})_{3}$
CH(C2H5)CO2] 2] was
synthesised in the laboratory. Transparent and crack-free films were
fabricated on pre-cleaned quartz substrates by spin coating. The structural
and optical properties of films annealed at different temperatures have been
investigated. The as-fired film was found to be amorphous while crystalline,
cubical phase structure film was obtained after annealing at 550 °C for
one hour in air. The films are polycrystalline in structure with the lattice
constants of a = 3.90 Å. The grain sizes of the films annealed at 450, 500
and 550 °C were found to be 26.4, 31.8 and 35.2 nm, respectively. The
optical constants of the films (refractive index, extinction coefficient,
optical conductivity, complex dielectric constant, and energy band gap) were
determined from the transmittance spectra. The refractive indexes of the
films were found to increase while the optical band gaps were found to
decrease with annealing temperature. The optical dispersion data are also
analysed in the light of single oscillator model and are discussed.
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- Research Article
- Information
- Copyright
- © EDP Sciences, 2009
References
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